Wireless base station apparatus and wireless communication method

ABSTRACT

Transmission diversity and adaptive array antenna transmission is executed with respect to a user to which a shared channel is assigned, or a pilot channel is shared a like a shared channel. By this means it is made possible to secure a large number of users without code resource shortages even where adaptive array antenna is applied to a shared channel.

TECHNICAL FIELD

The present invention relates to digital wireless communication systems,and more particularly, to wireless base station apparatus and wirelesscommunication methods for use with CDMA (Code Division Multiple Access).

BACKGROUND ART

In digital wireless communication systems, adaptive array antenna(hereinafter “AAA”) techniques are used to adaptively controldirectivity by multiplying weight to an antenna output from a pluralityof antenna elements. AAA techniques utilize a direction of arrival of asignal is different from one another and suppress interference signalsby adaptively controlling directivity. For this reason, adaptive arrayantenna techniques are suitable for removing interference signal on asingle channel.

In digital wireless communication, there are cases where AAAtransmission is performed using the weight used upon AAA reception. Interms of AAA transmission, there is also a method whereby a direction ofarrival is estimated in respect to a signal from a user and the weightis calculated so as to turn the directivity in this direction, and AAAtransmission is performed using the calculated weight.

Upon performing AAA transmission, channel estimation takes place usingthe reference signals transmitted by directivity transmission. In thiscontext, an individual pilot channel S-CPICH (Secondary-Common PilotIndicator CHannel) signal is used per user as a reference signal.

In order to transmit large-volume packet data on downlink channels, theimplementation of shared channels such as the DSCH (Downlink SharedChannel) whereby a plurality of communication terminals (users) use onechannel has come under consideration in recent years. For instance, whenperforming transmission using the DSCH, each user uses its dedicatedchannel to transmit control data to control transmit power and maintainsynchronization, while receiving information as to whether thetransmitted DSCH signal addresses the user as well as information on thetransmission rate of DSCH.

Furthermore, a communication terminal receives dedicated channels andmakes decisions as to whether these channels address the terminalapparatus, and, when they do, interprets the information regarding thetransmission rate of DSCH from the dedicated channels and receives anddemodulates the signals transmitted by DSCH.

Where transmission diversity of CDMA/FDD (Frequency Division Duplex) of3GPP (3rd Generation Partnership Project) is employed, that is, wheretransmission diversity and AAA transmission are applied to DSCH, CPICHis transmitted from two pairs of array antennas by means of AAA, whichnecessitates CIPCHs by double the number of users. As a result, coderesources run short and the number of users is limited.

DISCLOSURE OF INVENTION

The present invention aims to provide a wireless base station apparatusand wireless communication methods whereby such wireless communicationthat secures a large number of users without code resource shortages canbe performed where adaptive array antenna transmission is applied toshared channels.

When shared channels such as DSCH are transmitted by means of combiningAAA transmission and transmission diversity, pilot channels used asreference signals need to be sent by AAA transmission to calculatefeedback information for the transmission diversity in communicationterminals. As a result, the number of spreading codes used for thesepilot channels grows. Focusing on this point, the present inventors havearrived at the present invention upon discovering that code resourceshortages due to the growth of pilot channels in number can be avoidedby sharing pilot channels and by switching the directivity of the pilotchannels according to the switching of the shared channel.

Furthermore, since DSCH transmits control data except data, each useruses its dedicated channel to transmit control data and control transmitpower and maintain synchronization. When transmission diversity isperformed in this context, the dedicated channels appended to DSCHbecome necessary corresponding to the number of diversity antennas(normally two). Because of this, the number of spreading codes used fordedicated channels grows.

Furthermore, one major aspect of these dedicated channels is thetransmission of control data, and so the transmission rates are low.This makes it possible to perform communication using low spreadingfactors, and the use of transmission diversity or AAA transmission is ofminor merit.

Focusing on this point, the present inventors have arrived at thepresent invention upon discovering that by using AAA transmission andtransmission diversity to both DSCH and the dedicated channel appendedthereto of a user to which DSCH signal is transmitted, and by not usingtransmission diversity on the dedicated channel that is appended to DSCHwith regard to a user DSCH signal is not transmitted to, it becomesunnecessary to assign pilot channels for transmission diversity to usersto which DSCH signal is not transmitted, and code resource shortagesresulting from the growth of pilot channels in number can be avoided.

In short, the above object can be achieved by such means as performingtransmission by combining transmission diversity and adaptive arrayantenna transmission in respect to users to which a shared channel isassigned or by sharing pilot channels like shared channels.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration of a wireless basestation apparatus according to Embodiment 1 of the present invention;

FIG. 2 is a block diagram showing a configuration of a communicationterminal apparatus that performs wireless communication with thewireless base station apparatus shown in FIG. 1;

FIG. 3 is a drawing illustrating the timing of transmission in thewireless base station apparatus shown in FIG. 1;

FIG. 4A is a drawing illustrating the shifting of pilot channeldirectivity;

FIG. 4B is a drawing illustrating the shifting of pilot channeldirectivity;

FIG. 4C is a drawing illustrating the shifting of pilot channeldirectivity;

FIG. 5 is a drawing illustrating the details of the timing oftransmission in the wireless base station apparatus shown in FIG. 1;

FIG. 6 is a block diagram showing a configuration of a wireless basestation apparatus according to Embodiment 2 of the present invention;and

FIG. 7 is a drawing illustrating the timing of transmission in thewireless base station apparatus shown in FIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

Now with reference to the accompanying drawings, embodiments of thepresent invention will be described.

(Embodiment 1)

A case will be described here with the present embodiment where AAAtransmission and transmission diversity are applied to a shared channelto perform transmission.

FIG. 1 is a block diagram showing a configuration of a wireless basestation apparatus according to Embodiment 1 of the present invention.The bold lines in FIG. 1 denote information for 3 antenna elements.

A case will be described here with FIG. 1 where 3 antenna elementsconstitute an array antenna and diversity is performed by 2 arrayantennas. However, the present invention is not limited to such case andis applicable to cases where an array antenna comprises any number ofantenna elements other than 3. Also, the present embodiment describes acase with 3 users, yet the present invention can similarly be applied tocases with 2 users or 4 or more users. The present embodimentfurthermore describes a case where DSCH is used as a shared channel(SCH) and S-CPIH as a common pilot channel (CPICH).

An uplink channel signal (received signal) from a communication terminalapparatus is received in reception RF section 102 a via array antenna111 a which is antenna 1. In reception RF section 102 a the receivedsignal is subjected to predetermined wireless reception processing(i.e., down-conversion, amplification, A/D conversion, etc.), and thesignal after the wireless reception processing is output to receivedsignal processing section 103.

Also, a received signal is received in reception RF section 102 b viaantenna 101 b which is antenna 2. In reception RF section 102 b thereceived signal is subjected to predetermined wireless receptionprocessing, and the signal after the wireless reception processing isoutput to received signal processing section 103.

Received signal processing section 103 is provided per user, and eachone comprises AAA reception section 104 a and 104 b, and diversitycombining section 105. Furthermore, AAA reception section 104 a and 104b each comprises matched filter (MF) 1041, received weight combiningsection 1042, and weight renewing section 1043. Since the operations ofAAA reception section 104 a and 104 b are the same, AAA receptionsection 104 a will be used here for description.

The signal output from reception RF section 102 a is subjected tocorrelation calculation in MF 1041 in AAA reception section 104 a usingthe spreading code used by the communication terminal. The output ofthis correlation calculation is sent to received weight combiningsection 1042 and to weight renewing section 1043.

In weight renewing section 1043, a direction of arrival of the receivedsignal is estimated, and the received weight is calculated based on theresult of this arrival direction estimation. The received weight is thenoutput to received weight combining section 1042. The received weight isalso output from weight renewing section 1043 to transmission weightselection section 111 for use as a transmission weight in transmissionweight selection section 111.

In received weight combining section 1042, AAA reception processing uponthe correlation output from MF 1041 takes place using the receivedweight obtained in weight renewing section 1043, and the signal afterthe AAA reception processing is output to diversity combining section105.

In diversity combining section 105, signals after the AAA receptionprocessing from all AAA reception sections 104 a and 104 b are combinedto obtain a received signal. Incidentally, when the current user isassigned to DSCH, received signals from this user contain feedbackinformation (phase difference information or phase difference/amplitudeinformation) for transmission diversity, and so this feedbackinformation is then output to feedback information selection section106.

SCH assignment section 107 selects a user's dedicated channel that is tobe transmitted by DSCH, based on user assignment information. Sincetransmission diversity and AAA transmission are applied to thetransmission data (e.g., destination and transmission rate) of theuser's dedicated channel transmitted by DSCH along with DSCH andS-CPICH, the transmission data of the DSCH-transmitted user's dedicatedchannel is multiplexed with DSCH and S-CPIH in adder 109 for antenna 110a and in adder 110 for antenna 101 b respectively and then output todiversity multiplication section 112 a and 112 b.

User assignment information is also output to feedback informationselection section 106, where the DSCH-transmitted user's feedbackinformation is selected. In feedback information selection section 106,then, a weight for transmission diversity is calculated based on theselected feedback information. For instance, a weight such as one thatfixes a basis with one antenna while giving another antenna a phasedifference is calculated based on phase difference information which isfeedback information. This transmission diversity weight is output todiversity multiplication section 112 a and 112 b.

In diversity multiplication section 112 a and 112 b, the signal in whichan dedicated channel, DSCH, and S-CPIH are multiplexed is multiplied bya weight of the feedback information selected in feedback informationselection section 106, and the signal after the multiplication isrespectively output to directivity multiplication section 113 a and 113b.

Since user assignment information is output also to transmission weightselection section 111, weight selection section 111 selects atransmission weight for user to receive DSCH-transmitted signals. Theselected transmission weight is output to directivity multiplicationsection 113 a and 113 b.

In directivity multiplication section 113 a and 113 b, outputs fromdiversity multiplication sections 112 a and 112 b are multiplied by thetransmission weight selected in transmission weight selection section111, and the signal after the multiplication is output to transmissionRF section 115 a and 115 b respectively. Outputs for one antenna elementof antenna 101 a are sent to adder 114.

Meanwhile transmission data (destination, transmission rate) of userdedicated channels that are not transmitted by DSCH are multiplexed inadder 108 and output to adder 114. In adder 114, the output fromdirectivity multiplication section 113 a and transmission data of theuser dedicated channels that are not transmitted by DSCH are multiplexedand output to transmission RF section 115 a.

In transmission RF section 115 a, outputs from directivitymultiplication section 113 a and 113 b and from adder 114 are subjectedto predetermined wireless transmission processing (D/A conversion,amplification, up-conversion, etc.). The signal after the wirelesstransmission processing is transmitted as a downlink channel signal viaantenna 101 a to communication terminal apparatus. In transmission RFsection 115 b, outputs from directivity multiplication section 113 a and113 b are subjected to predetermined wireless processing. The signalafter the wireless transmission processing is transmitted as a downlinkchannel signal via antenna 101 a to communication terminal apparatus.

At this point, the DSCH-transmitted user's dedicated channel, DSCH, andS-CPIH are transmitted from antenna 101 a and from 101 b withtransmission diversity and AAA transmission applied, and thetransmission of user dedicated channels that are not transmitted by DSCHdedicated channel is performed by one antenna element of antenna 101 b.

FIG. 2 is a block diagram showing a configuration of a communicationterminal apparatus that performs wireless communication with thewireless base station apparatus shown in FIG. 1.

The downlink channel signal (received signal) transmitted from thewireless base station apparatus is received in reception RF section viaantenna 201. In reception RF section 202, the received signal issubjected to predetermined reception processing (down conversion,amplification, A/D conversion, etc.), and the signal after the wirelessreception processing is output to DCH reception section 203. The signalafter the wireless reception processing is stored also in memory 205.

In DCH reception section 203, the signal after the wireless receptionprocessing is subjected to dispreading processing by the spreading codeused in the wireless base station apparatus, and demodulation processingwith the signal after the dispreading processing takes place to obtaindestination information and transmission rate information transmitted bythe dedicated channel. Destination information and transmission rateinformation are then output to deciding section 204.

Deciding section 204 makes decisions as to whether the destinationinformation addresses the terminal, and, when it does, interprets andoutputs the transmission rate to shared channel reception section 206and to transmission diversity pilot channel reception section 207.

In shared channel reception section 206, the signal stored in memory 205is subjected to modulation processing using the transmission rateinterpreted in deciding section 204, and, after decoding a sharedchannel, received signal is obtained.

In transmission diversity pilot channel reception section 207, on theother hand, feedback information for transmission diversity is generatedby using the known signals for transmission diversity from among thesignals stored in memory 205 at the transmission rate interpreted indeciding section 204. This feedback information is output tomultiplexing section 208.

Multiplexing section 208 multiplexes feedback information andtransmission signals of an dedicated channel and transmits the result totransmission RF section 209 when DSCH addresses the terminal apparatus.In transmission RF section 209, predetermined wireless receptionprocessing (D/A conversion, amplification, up-conversion, etc.) for themultiplexed signal takes place. The signal after the wirelesstransmission processing is transmitted as an uplink channel signal to awireless base station apparatus via antenna 201.

Next a case will be described here where a wireless communication methodaccording to the present embodiment is performed with a wireless basestation apparatus and communication terminal apparatus of the aboveconfigurations. A case will be described here where user (a) is selectedas a user to receive DSCH-transmitted signals.

To begin with, in this context, user (a) is determined to be the objectof DSCH assignment in the wireless resource management section. Thewireless base station apparatus transmits this user assignmentinformation (destination information) and transmission rate informationto the communication terminal apparatus using user (a)'s dedicatedchannel, whereupon an S-CPICH (transmission diversity pilot channel)signal is also transmitted to the communication terminal apparatus.

User (a)'s communication terminal apparatus receives the downlinkchannel signal from the wireless base station apparatus, modulates thededicated channel signal appended to DSCH in DCH reception section 203,confirms that DSCH addresses the communication apparatus in decidingsection 204, and interprets the transmission rate. Then, S-CPICH isreceived in transmission diversity pilot channel reception section 207at the above transmission rate, and feedback information fortransmission diversity is generated by using the known signals with thisS-CPICH. This feedback information is then transmitted on an uplinkchannel to the wireless base station apparatus.

The base station apparatus receives the uplink channel signal andobtains the received signal in user (a)'s received signal processingsection 103 and outputs the feedback information contained in thereceived signal to feedback information selection section 106. Inaccordance with the feedback information from user (a)'s communicationterminal apparatus, feedback information selection section 106 thenoutputs a weight for transmission diversity that corresponds to user (a)to diversity multiplication section 112 a and 112 b.

User assignment information determined in the wireless resourcemanagement section is sent to SCH assignment section 107. SCH assignmentsection 107 controls in a way that user (a)'s dedicated channel (DCH)data (destination information, transmission rate information, etc.) thatis transmitted by DSCH is output to adder 109 and 110, while user (b)'sand user (c)'s dedicated channel (DCH) data that are not transmitted byDSCH are output to adder 108.

In adder 109 and 110, DSCH, user (a)'s dedicated channel (DCH), andS-CPICH that are transmitted from antenna 101 a are respectivelymultiplexed. The signal multiplexed in adder 109 is output to diversitymultiplication section 112 a and there multiplied by the weight obtainedbased on feedback information from user (a). Moreover, the signalmultiplexed in adder 110 is output to diversity multiplication section112 b and there multiplied by the weight obtained based on feedbackinformation from user (a).

The signal multiplied by a weight for transmission diversity is outputto directivity multiplication section 113 a and 113 b respectively andthere multiplied by a transmission weight for user (a). The transmissionweight used here is one obtained in the AAA reception section thatcorresponds to user (a)'s received signal processing section 103 basedon a received signal's direction of arrival.

The signal multiplied by a transmission weight is respectivelytransmitted from antenna 101 a and 101 b as a downlink channel signalvia transmission RF section 115 a and 115 b. From one antenna element ofantenna 110 a, signals for dedicated channels (DCH) that are nottransmitted by DSCH are transmitted with user (a)'s signal that ismultiplied by up to a transmission weight.

User (a)'s communication terminal apparatus receives the downlinkchannel signal from the wireless base station apparatus, modulates thededicated channel (DCH) signal appended to DSCH in DCH reception section203, confirms that DSCH addresses the communication apparatus indeciding section 204, and interprets the transmission rate. DSCH signalsare then received at this transmission rate.

Thus transmission diversity and AAA transmission are applied withrespect to a user's (user (a)) dedicated channel (DCH) that istransmitted by DSCH dedicated channel (DCH), and the dedicated channels(DCH) for users (user (b), user (c)) that are not transmitted by DSCHare transmitted without the application of transmission diversity.

The timing user (a) through user (c) share DSCH to perform transmissionwill be described with FIG. 3. FIG. 3 is a drawing showing the timing oftransmission in the wireless base station apparatus shown in FIG. 1.

In this context, from time kT user (a) is assigned DSCH, from time(k+n1)T user (b) is assigned DSCH, and from time (k+n2)T user (c) isassigned DSCH.

From time kT to time (k+n1)T, user (a) is assigned DSCH, and accordinglydestination information and transmission rate information aretransmitted to user (a) using an dedicated channel (DCH), whereupontransmission diversity and AAA transmission are applied to user (a)'sdedicated channel (DCH), DSCH, and to S-CPICH. As for AAA transmission,as shown in FIG. 4A, directivity 401 in respect to user (a) is used. Incontrast, user (b) and user (c) are not assigned DSCH, and so theirdedicated channels, DSCH, and S-CPICH are transmitted using one antennawithout the application of transmission diversity.

From time (k+n1)T to time (k+n2)T, user (b) is assigned DSCH, andaccordingly destination information and transmission rate informationare transmitted to user (b) using an dedicated channel, whereupontransmission diversity and AAA transmission are applied to user (b)'sdedicated channel, DSCH, and to S-CPICH. As for AAA transmission, asshown in FIG. 4B, directivity 402 in respect to user (b) is used. Incontrast, user (a) and user (c) are not assigned DSCH, and so theirdedicated channels, DSCH, and S-CPICH are transmitted using one antennawithout the application of transmission diversity.

From time (k+n2)T to time (k+n3)T, user (c) is assigned DSCH, andaccordingly destination information and transmission rate informationare transmitted to user (c) using an dedicated channel, whereupontransmission diversity and AAA transmission are applied to user (c)'sdedicated channel, DSCH, and to S-CPICH. As for AAA transmission, asshown in FIG. 4C, directivity 403 in respect to user (c) is used. Incontrast, user (a) and user (b) are not assigned DSCH, and so theirdedicated channels, DSCH, and S-CPICH are transmitted using one antennawithout the application of transmission diversity.

As described above, each user's communication terminal apparatus obtainsdestination information and transmission rate information in the shadedsection in its dedicated channel (DCH) as shown in FIG. 3, interpretsthe destination, interprets transmission rate information when thecommunication terminal is the destination, and receives DSCH signal bythis transmission rate.

By thus applying transmission diversity only with respect to andedicated channel of a user to which DSCH is assigned, there is no needto assign pilot cannels to users to which DSCH is not assigned. Thismakes it possible to solve code resource shortages resulting from thegrowth of pilot channels in number.

There are cases where an dedicated channel appended to DSCH transmitscontrol information alone as well as cases where this dedicated channeltransmits sound and data and the like with control information. Whencontrol information alone is transmitted, the data volume is extremelylow. So other users suffer little interference, and there is no need toreduce the transmission power of communication terminals by means of AAAreception. As a result, it is possible to reduce AAA processing load byapplying AAA reception only with respect to received signals from a userDSCH is assigned to.

In the above description, the wireless base station apparatus receivessignals from all users by means of AAA reception. However, a case willbe described below with FIG. 5 where AAA reception is applied only toreceived signals from a user to which DSCH is assigned. In this context,in the wireless base station apparatus, the AAA reception section isswitched for a DSCH-assigned user and then assigned, and AAA receptionstarts early enough to make the weight calculation for AAA transmissioncertainly possible.

Assuming that from time kT user (a) is assigned DSCH, from time (k+n1)Tuser (b) is assigned DSCH, and from time (k+n2)T user (c) is assignedDSCH, and that the time to calculate transmission weight for AAAtransmission is mT, the AAA reception section is assigned as follows:

-   Time kT˜time (k+n1−m)T: user (a)-   Time (k+n1−m)T˜time(k+n1)T: user (a) and user (b)-   Time (k+n1)T˜time(k+n2−m)T: user (b)-   Time (k+n2−m)T˜time(k+n2)T: user (b) and user (c)-   Time (k+n2)T˜time (k+n3)T: user (c).

By thus assigning AAA reception sections according to DSCH assignments,it suffices to provide AAA reception sections only where receptionpreparation time mT for AAA reception and the time intervals (n1, n2,n3, . . . ) in user assignments overlap. In this example, it suffices toprovide two AAA reception sections for three users.

Generally, since the number of users assigned to DSCH is large andvaries from dozens up to approximately one hundred, by reducing thenumber of AAA reception sections, it is possible to make hardconfigurations smaller and to reduce the processing load substantially.

(Embodiment 2)

A case will be described here with this embodiment where transmissiondiversity is not performed and code resource shortages due to the growthof pilot channels in number are avoided by means of sharing a pilotchannel and by switching the directivity of the pilot channel accordingto the switching of a shared channel.

FIG. 6 is a block diagram showing a configuration of a wireless basestation apparatus according to Embodiment 2 of the present invention.The bold lines in FIG. 6 denote information for 3 antenna elements.

A case will be described here with FIG. 6 where 3 antenna elementsconstitute an array antenna. However, the present invention is notlimited to such case and is applicable to cases where an array antennacomprises any number of antenna elements other than 3. Also, the presentembodiment describes a case with 3 users, yet the present invention cansimilarly be applied to cases with 2 users or 4 or more users. Thepresent embodiment furthermore describes a case where DSCH is used as ashared channel (SCH) and S-CPICH as a common pilot channel (CPICH).

An uplink channel signal (received signal) from a communication terminalapparatus is received in reception RF section 602 via antenna 601. Inreception RF section 602, the received signal is subjected topredetermined wireless reception processing (i.e., down-conversion,amplification, A/D conversion, etc.), and the signal after the wirelessreception processing is output to received signal processing section603.

Received signal processing section 603 is provided per user, and eachone comprises AAA reception section 604. Furthermore, AAA receptionsection 604 each comprises matched filter (MF) 6041, received weightcombining section 6042, and weight renewing section 6043.

The signal output from reception RF section 602 is subjected tocorrelation calculation in MF 6041 in AAA reception section 604 usingthe spreading code used by the communication terminal. The output ofthis correlation calculation is sent to received weight combiningsection 6042 and to weight renewing section 6043.

In weight renewing section 6043, a direction of arrival of the receivedsignal (user) is estimated, and the received weight is calculated basedon the result of this arrival direction estimation. The received weightis then output to received weight combining section 6042. The receivedweight is also output from weight renewing section 6043 to transmissionweight selection section 608 to be used as a transmission weight intransmission weight selection section 608.

In received weight combining section 6042, AAA reception processing uponthe correlation output from MF 6041 takes place using the receivedweight obtained in weight renewing section 6043 to obtain the receivedsignal.

In SCH assignment section 605, a user's dedicated channel (DCH) that isto be transmitted by DSCH is selected based on user assignmentinformation. Since transmission diversity and AAA transmission areapplied to the transmission data (e.g., destination and transmissionrate) of the user's dedicated channel (DCH) transmitted by DSCH alongwith DSCH and S-CPICH, the transmission data of the DSCH-transmitteduser's dedicated channel is multiplexed with DSCH and S-CPIH in adder607 and then output to directivity multiplication section 609.

The user assignment information is also output to transmission weightselection section 608, and accordingly, transmission weight selectionsection 608 selects a transmission weight for user to receiveDSCH-transmitted signals. The selected transmission weight is output todirectivity multiplication section 609.

In directivity multiplication section 609, the output from adder 607 ismultiplied by the transmission weight selected in transmission weightselection section 608, and the signal after the multiplication is outputto transmission RF section 611 respectively. Incidentally, output forone antenna element of antenna 601 is sent to directivity multiplicationsection 609.

Meanwhile the transmission data (destination, transmission rate) of userdedicated channels (DCH) that are not transmitted by DSCH aremultiplexed in adder 606 and output to adder 610. In adder 610, theoutput from directivity multiplication section 609 and the transmissiondata of user dedicated channels that are not transmitted by DSCH aremultiplexed and output to transmission RF section 611.

In transmission RF section 611, outputs from directivity multiplicationsection 609 and from adder 610 are subjected to predetermined wirelesstransmission processing (D/A conversion, amplification, up-conversion,etc.). The signal after the wireless transmission processing istransmitted as a downlink channel signal via antenna 601 tocommunication terminal apparatus.

At this point, transmission diversity and AAA transmission are appliedto transmit the DSCH-transmitted user's dedicated channel (DCH), DSCH,and S-CPICH from antenna 601, and the transmission of user dedicatedchannels that are not transmitted by DSCH is performed by one antennaelement of antenna 601.

Next a case will be described here where a wireless communication methodaccording to the present embodiment is implemented using a wireless basestation apparatus of the above configuration and communication terminalapparatus shown in FIG. 2. A case will be described here where user (a)is selected as a user to transmit DSCH to.

User assignment information determined in the wireless resourcemanagement section is sent to SCH assignment section 605. SCH assignmentsection 605 controls such that user (a)'s dedicated channel (DCH) data(destination information, transmission rate information, etc.) that istransmitted by DSCH is output to adder 607 while user (b)'s and user(c)'s dedicated channel (DCH) data that are not transmitted by DSCH areoutput to adder 606.

In adder 607, DSCH, user (a)'s dedicated channel (DCH), and S-CPICH thatare transmitted from antenna 601 are multiplexed. The signal multiplexedin adder 607 is output to directivity multiplication section 609 andthere multiplied by a transmission weight that corresponds to user (a).The transmission weight used here is one obtained in the AAA receptionsection in user (a)'s received signal processing section 603 based on areceived signal's direction of arrival.

The signal multiplied by transmission weight is transmitted as adownlink channel signal from antenna 601 via transmission RF section611. Incidentally, from one antenna element of antenna 601, signals fordedicated channels (DCH) that are not transmitted by DSCH aretransmitted with user (a)'s signal that is multiplied by up to atransmission weight.

User (a)'s communication terminal apparatus receives the downlinkchannel signal from the wireless base station apparatus, modulates thededicated channel (DCH) signal appended to DSCH in DCH reception section203, confirms that DSCH addresses the communication apparatus indeciding section 204, and interprets the transmission rate. DSCH signalsare then received at this transmission rate.

The timing user (a) through user (c) share DSCH to perform transmissionwill be described with FIG. 7. FIG. 7 is a drawing showing the timing oftransmission in the wireless base station apparatus shown in FIG. 6.

In this context, from time kT user (a) is assigned DSCH, from time(k+n1)T user (b) is assigned DSCH, and from time (k+n2)T user (c) isassigned DSCH.

From time kT to time (k+n1)T, user (a) is assigned DSCH, and accordinglydestination information and transmission rate information aretransmitted to user (a) using an dedicated channel, whereupon AAAtransmission is applied to user (a)'s dedicated channel (DCH), DSCH, andto S-CPICH. As for AAA transmission, as shown in FIG. 4A, directivity401 in respect to user (a) is used.

From time (k+n1)T to time (k+n2)T, user (b) is assigned DSCH, andaccordingly destination information and transmission rate informationare transmitted to user (b) using an dedicated channel, whereupon AAAtransmission are applied to user (b)'s dedicated channel, DSCH, and toS-CPICH. As for AAA transmission, as shown in FIG. 4B, directivity 402in respect to user (b) is used.

From time (k+n2)T to time (k+n3)T, user (c) is assigned DSCH, andaccordingly destination information and transmission rate informationare transmitted to user (c) using an dedicated channel, whereupontransmission diversity and AAA transmission are applied to user (c)'sdedicated channel, DSCH, and to S-CPICH. As for AAA transmission, asshown in FIG. 4C, directivity 403 in respect to user (c) is used.

As described above, each user's communication terminal apparatus obtainsdestination information and transmission rate information in the shadedsection in its dedicated channel as shown in FIG. 7, interprets thedestination, interprets transmission rate information when thecommunication terminal is the destination, and receives DSCH signal atthis transmission rate.

By thus sharing a pilot channel as well and by switching the directivityof the pilot channel according to the switching of a shared channel, itis possible to avoid code resource shortages due to the growth of pilotchannels in number.

With the present embodiment too, similar to Embodiment 1, it is possibleto reduce the number of AAA reception sections and to make hardconfigurations small to reduce the processing load substantially by wayof assigning AAA reception sections to users in accordance with DSCHassignment.

The present invention is not limited to above Embodiment 1 and 2 and canbe implemented in various modified forms. For instance, althoughEmbodiment 1 and 2 describe cases where a wireless base stationapparatus uses a received weight obtained from a received signal'sdirection of arrival as a transmission weight, the present invention isnot limited to such case and applicable to cases where a transmissionweight is obtained anew from a received signal's direction of arrivaland this weight is applied upon performing AAA transmission.

Furthermore, although Embodiment 1 and 2 describe cases where DSCH isused as a shared channel and S-CPICH as a pilot channel, the presentinvention is not limited to such case, and a channel other than DSCH maybe used for a shared channel as long as it is a channel for common useby a plurality of users, and a channel other than S-CPICH may be used asa pilot channel as long as it is a channel capable of directivitytransmission and capable of transmitting known signals.

Further still although Embodiment 1 and Embodiment 2 describe caseswhere dedicated channels for users that are not assigned to a sharedchannel are transmitted from one antenna, the present invention canapply AAA transmission to dedicated channels for users that are notassigned to a shared channel. In such case, for instance, the outputafter the multiplexing of dedicated channels for users that are notassigned to a shared channel are to which a directivity transmissionweight is multiplied.

The wireless base station apparatus and wireless communication methodsunder the present invention enable it to secure a large number of userswithout incurring code resource shortages by for instance performingtransmission diversity and adaptive array antenna transmission to usersthat are assigned shared channel and by sharing a pilot channel like ashared channel.

This application is based on Japanese Patent Application No. 2000-389473filed on Dec. 21, 2000, entire content of which is expresslyincorporated by reference herein.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use with digital wirelesscommunication systems, and more particularly, for use with wireless basestation apparatus and wireless communication methods for use with CDMA(Code Division Multiple Access).

1. A wireless base station apparatus, comprising: a diversity antenna,each constituted with a plurality of antenna elements and executingtransmission diversity, a selection section that selects a user that isto be an object of transmission by a shared channel, and a first weightmultiplying section that multiplexes the shared channel and a controlchannel that is different from the shared channel and that contains aknown signal for said transmission diversity to multiply weight for saidtransmission diversity to the user selected in said selection section,wherein transmission diversity is executed only with respect to the userto which a shared channel is assigned.
 2. The wireless base stationapparatus according to claim 1, wherein said control channel is anappended channel appended to the shared channel and/or is a pilotchannel.
 3. The wireless base station apparatus according to claim 2,wherein the pilot channel is shared by the user to which a sharedchannel is assigned.
 4. The wireless base station apparatus according toclaim 1, further comprising a second weight multiplying section thatmultiplies a weight for directivity transmission to an out S put fromsaid first weight multiplying section.
 5. The wireless base stationapparatus according to claim 1, further comprising: a directivityreception section that receives an uplink channel signal from acommunication terminal apparatus by means of directivity reception, andan assignment section that assigns said directivity reception section tothe user to which a shared channel is assigned according to theassignment of the shared channel.
 6. A wireless communication terminalapparatus that performs wireless communication with said wireless basestation apparatus according to claim
 1. 7. A wireless base stationapparatus, comprising: a diversity antenna, each constituted with aplurality of antenna elements and executing transmission diversity, aselection section that selects a user that is to be an object oftransmission by a shared channel that contains a known signal for saidtransmission diversity, and a first weight multiplying section thatmultiplies weight for said transmission diversity to the shared channelassigned to the user selected in said selection section, whereintransmission diversity is executed only with respect to the user towhich a shared channel is assigned.
 8. A wireless base station apparatuscomprising: a selection section that selects a user that is to be anobject of transmission by a shared channel and an appended channelappended to the shared channel, and a weight multiplying section thatmultiplexes the shared channel and the appending channel to multiplyweight for directivity transmission to the user selected in saidselection section, wherein the pilot channel is shared by the user towhich a shared channel is assigned and executes directivity transmissionwith respect to said user to which a shared channel is assigned.
 9. Awireless communication method comprising: a selection step whereby auser that is to be an object of transmission by a shared channel isselected, a first weight multiplying step whereby the shared channel anda control channel that is different from the shared channel and thatcontains a known signal for said transmission diversity are multiplexedto multiply weight for said transmission diversity to the user selectedin said selection section, and a second weight multiplying step wherebyweight for directivity transmission is multiplied to an output from theforegoing weight multiplying step, wherein transmission diversity isexecuted only with respect to the user to which a shared channel isassigned.
 10. A wireless communication method comprising: a selectionstep whereby a user that is to be an object of transmission by a sharedchannel and an appended channel appended to the shared channel isselected, and a weight multiplying step whereby the shared channel andthe appended channel are multiplexed to multiply weight for transmissiondiversity to the user selected in said selection step, wherein the pilotchannel is shared by the user to which a shared channel is assigned andexecutes directivity transmission with respect to said user to which ashared channel is assigned.